In this modern world it's hard to repair a lot of electronics because:
The manufacturers do not provide schematics. (Back in the day you'd likely find the schematic for your new radio glued to the inside of the back cover!)
Even with a schematic you may never know what chips are on there. They have obscured part numbers.
Even with all that you probably cannot buy any custom chips the thing uses.
Often chips require programming, microcontrollers, FPGA etc. The manufactures will not give you that code.
That's before we even think of the difficulty of replacing SMT devices, especially BGAs. Which is perhaps the easy part. Even a small repair shop can afford to acquire hot air rework stations, microscopes etc. As Louis Rossmann demonstrates.
And of course, is it economically worth the bother to put all that time and effort in?
The Raspberry Pi is a typical example of all the above.
Louis Rossmann and others do an amazing job of fixing Mac books. Given all the roadblocks I mention. He has to harvest those unobtainable parts from other dead Mac motherboards. At least there is a little demand to fix Macs as they are such expensive devices.
In the USA there is a "right to repair" campaign going on https://www.popularmechanics.com/techno ... -nebraska/
to try and get the law to prevent manufactures from putting these roadblocks to repair in place.